In general, ammunition consists of a bullet which functions as a projectile, a propelling charge which functions as a propellant, a percussion cap which ignites the propelling charge, and a cartridge case which covers the bullet, propelling charge and percussion cap.
Especially, when the bullet is shot from a gun or a cannon, it is propelled by high pressure gas generated by combustion of the propelling charge, thereby having the effect of casualty and destruction using its penetration and fragments.
Initially, the bullet was developed and researched with an emphasis on its killing power. However, in modem times, it has been researched with an emphasis on improving of its functions such as effective range and accuracy rate.
As shown in FIG. 1, a conventional bullet 10 consists of a head part 2, and a tail part 4 which is extended to the rear side of the head part 2 and formed into a streamline shape. Since the bullet 10 has the streamlined tail part 4, it is possible to efficiently prevent irregular air-flow like vortex which may generate at the rear side of the bullet 10 during flight. However, due to the streamlined tail part 4, a bottom surface of the bullet, which receives an impelling force in a gun barrel, becomes too small and thus the propelling efficiency of the bullet is reduced. Further, there is another problem in that a length of the bullet 10 becomes excessively longer.
In FIG. 2, a bullet which is developed in order to solve the problems is shown. The bullet 10 consists of a head part 2 and a tail part 4 which is extended to the rear side of the head part 2 and formed into a boat-tail shape. Since the tail part 4 has the boat-tail shape, it is possible to satisfy the problem of the impelling force in the gun barrel to a certain degree, but there is another problem in that irregular air-flow like vortex is generated at the rear side of the tail part 4.
And in case of a bullet disclosed in Korean Patent No. 0437008, the bullet has a guiding body for inducing an air flow, and an inclined groove is formed in the outer surface of the guiding body.
Accordingly, the bullet shot from a gun is rotated right along fringing grooves, and then from a point of time when the bullet leaves the gun, rotational force which rotates the bullet left is applied to the bullet by the inclined groove. Thus, it is prevented that a trajectory of the bullet is curved right by centrifugal force, and thus the effective range of the bullet is relatively increased. The fringing grooves are spiral grooves formed inside the gun barrel. The fringing grooves function to provide stability to the bullet during flight and also provide rotational force necessary to increase destructive power of the bullet.
Meanwhile, as shown in FIG. 4, the center of pressure (CP) of a bullet is spaced apart from the center of gravity (CG) thereof and located between the CG and a front end of the bullet. Therefore, when the bullet is moved in the air, a yaw moment is generated as shown in FIG. 3, and thus a yaw angle is formed between a trajectory of the bullet and a symmetry axis which connects center points of the CP and CG Since the yaw angle has a large influence on the flight stability of the bullet, the bullet disclosed in Korean Patent No. 0437008 has an effect which increases the effective range thereof, but there is a problem that in that the yaw angle is increased during flight of the bullet and thus the accuracy rate is reduced.
Further, since the rotational force generated by the fringing grooves is offset by that of the inclined groove of the guiding body, the flight stability and the destructive power are deteriorated.
And since the guiding body has a flat rear surface, it is not possible to reduce or remove vortex generated at the rear side of the bullet during flight of the bullet, and thus the flight stability of the bullet is lowered and also it is limited to improve the effective range of the bullet.